We strongly recommend using an air pillow under your winter cover. The first reason to install a winter cover air pillow is to protect your pool from expanding ice. Instead, the weight of the water is evenly distributed around air pillow. This weight distribution can prevent the cover from sinking or tearing.Click to see full answer. Besides, what is the purpose of a pillow under a pool cover? The Purpose of a Pool Air Pillow By placing an air-filled pool pillow under your winter cover, you create a void in the water and on the top of the cover. When rain, snow, and ice accumulate, and pressure builds on the cover, the ice will expand inward toward the pillow.Additionally, does an above ground pool freeze solid? Aboveground Wall Collapse: If a pool begins to leak water, while the winter pool cover is frozen solid into the ice sheet – either the cover will rip, or the pool walls will collapse inward. Water expands about 9% when it freezes, so use enough Air Pillows to cover about 10% of the pool surface area. Regarding this, how many air pillows do I need for my pool? We suggest using the 4 x 4 Air Pillow on pools up to 24′ round. Use the 4 x 8 Air Pillow on pools 28′ round and up and on small oval pools. Use the 4 x 15 Air Pillow on Large (15 x 30 and larger) Oval aboveground pools.How do I keep my pool cover from sinking?Floating, solid pool covers should be pulled outward, to remove most wrinkles, and anchored solidly with water tubes or Aqua Blocks. These will hold the cover down, but not damage the cover or pool if they happen to fall into the pool. Pool Water Bags come in single and double tubes.